CORROSION UNDER INSULATION (CUI) A Nanotechnology Solution Explanation: Corrosion is the deterioration of essential properties in a metal, due to reactions with its surroundings. In the most common usage of the word, this means a loss of an electron of metal reacting with either water or oxygen. Corrosion Under Insulation (CUI) is a localized corrosion occurring at the interface of a metal surface and the insulation on that surface. This can be a particularly severe form of corrosion because of the difficulty in detection due to the corrosion occurring beneath insulation. Inspections for corrosion under insulation are generally not completed regularly enough to eliminate this problem due to the cost of insulation removal and replacement and cost of labor. Causes: Causes of CUI are similar in most ways to other types of corrosion, with the largest difference being the environment. Moisture combined with Oxygen of course is the largest contributing factor to corrosion. The closed environment of the insulation material over the pipe, tank or equipment creates conditions that encourage build up of moisture and resulting corrosion. The corrosion is often times more severe due to the insulation not allowing evaporation and the insulation acting as a carrier whereas moisture occurring in one area moves through the insulation to another area causing the corrosion to spread more rapidly. (See fig A) Figure A: Warm temperatures normally result in more rapid evaporation of moisture and reduced corrosion rates, however a surface covered with insulation creates an environment that holds in the moisture instead of allowing evaporation. Traditional thermal insulation materials contain chlorides. If they are exposed to moisture, chlorides may be released into a moisture layer on the pipeline surface and pitting/stress corrosion cracking may result. Acids, acid gases and strong bases like caustics and salts are aggressive corrosive agents and will not only cause but also accelerate existing CUI.
Costs: A study done by Exxon Mobil Chemical that was presented to the European Federation of Corrosion in September of 2003 indicated that: -The highest incidence of leaks in the refining and chemical industries is due to CUI and not to process corrosion; -Between 40 and 60 percent of piping maintenance costs are related to CUI. (1) Nanotechnology solution to CUI: The nanotechnology material in Nansulate coatings offers a new solution to the issue of CUI by introducing a coating that provides corrosion resistance and in addition, has a low thermal conductivity, which allows it to act as an insulator. One of the ways that CUI is dealt with when using traditional insulation is to use an anticorrosive coating underneath the insulation. This however does not alleviate the cost of removing and replacing the insulation for required corrosion inspections, and is also does not cure the environmental conditions that feed moisture build up beneath the insulation, which breeds corrosion and decreases the effectiveness of the insulation. Nansulate has four main characteristics that combat problems with CUI: 1. Low thermal conductivity (making it an insulator) 2. Corrosion Resistance 3. Resistance to moisture 4. Clear finish that allows visual inspection without insulation removal The nanotechnology material in Nansulate, Hydro-NM-Oxide, had a thermal conductivity of 0.017 W/mK. When fully cured, the coating contains approximately 70% Hydro-NM-Oxide and 30% acrylic resin and performance additive. Nansulate acts as an insulator by decreasing the amount of heat energy transferred. (See Appendix A, Temperature Gradient Chart, and Appendix B High Heat Empirical Calculation). The main benefit of using a thin film insulator as opposed to a traditional insulation, such as rock wool, is the increased longevity of the product and consistent insulating performance. A thin film nanotechnology coating is not subject to the same infiltration by dust, moisture, and microorganisms that reduce the effectiveness of traditional insulations. Due to the extreme hydrophobic nature of the nanotechnology material in Nansulate and the excellent adhesion to the surface, the coating retains corrosion resistance capabilities. For the ASTM B-117 it has passed 2000 hours, and in the more rigorous GM9540P Accelerated Corrosion Test it passed 24 cycles with no red rust present. The coating bond with the surface is one that repels excess moisture, instead of creating a desirable environment for the collection of moisture and resulting corrosion. The clear appearance of the coating makes visual inspection of the surface possible without damage to or removal of the coating. This combination of corrosion resistance and thermal
insulation in a clear coating is an innovation of nanotechnology that has not been available in the past. Conclusion: CUI has remained a prevalent problem in many industries. The cost of regular removal and replacement of insulation systems for corrosion inspections is one that is high, and has become problematic. Furthermore the traditional types of insulation create the perfect environment for moisture and resulting corrosion and create a conduit for that corrosion to spread more rapidly. Nanotechnology offers a way to for inspection personnel to inspect for corrosion more regularly and without removal of the insulation. This lowers both labor costs and costs of pipeline and equipment replacement due to CUI. Nansulate nanotechnology coatings offer a single product solution for corrosion resistance and insulation for pipelines, tanks and other plant equipment, which is easily applied, and maintains its effectiveness over time. (1) Reference: Insulation.org; is there a cure for corrosion under insulation? By Michael Lettich
Nansulate, patented Insulation Corrosion Prevention Mold Resistance Lead Encapsulation Industrial Nanotech, Inc. 800-767-3998 or 1-951-324-7121 801 Laurel Oak Dr. Ste. 702, Naples, FL 34108 www.industrial-nanotech.com USA corporate@industrial-nanotech.com Temperature Gradient Chart Demonstrates surface temperature differences achieved at various high temperatures Metal substrate Temp F of hot surface 100-120 170-190 191-210 211-230 Temp C of hot surface 38-49 77-88 89-99 100-110 3 coats (7 mils) Surface temperature difference shown 10-18F (5-10C) 20-35F (12-19C) 40-55F (20-27C) 60-75F (30-36C) 231-250 111-121 78-93 (37-44C) NOTE: Testing is currently being conducted on samples of higher dry mil thicknesses and at higher temperature ranges (250-400F) in order to show the extra benefit achieved with subsequent coats of Nansulate. Oil/Cylinder Gradient Demonstrates temperature differences achieved between heated oil and outer wall surface. 1) Substrate is 2" dia. stainless cylinder with wall thickness of.065 in. and 14 mils DFT (approx. 6 coats) of Nansulate Translucent High Heat. 2) Heated cooking oil to 325 deg F and poured into cylinder, taking temperature readings of oil and outer wall at the same time. 3) Following are temperatures at various points of cooling ; first figure is oil temperature, second is outer wall temperature. (all temperatures are in F) Oil Temp Outer Wall Temp 250 135 212 120 204 119 190 115 180 109 169 109 165 104 141 97 Sources for information: Temperature Gradient Chart: Figures were averaged from five testing applications. Applications include: Testing beginning May 4, 2005 by Protan S.A. on coated steel panels. Testing beginning May 31, 2005 by Protan S.A. on oil pipeline used on AM3 platform where petroleum is transferred to the continent. Testing done beginning July 4, 2005 by Nansulate Asia on coated metal panel. Testing beginning March 15, 2005 in house by Industrial Nanotech, Inc. on coated metal panels, Testing beginning June 2004 in house by Princeton Polymer Laboratory on coated metal panels. Oil/Cylinder Gradient: Testing information from Mobeq Industrial Products, Ltd from in house testing.
Nansulate High Heat Empirical Calculation Initial No.of Coats Surface Temp. / C 200 190 180 170 160 150 140 130 120 110 100 95 90 85 80 75 70 65 60 55 50 45 1 182 173 164 155 146 137 128 119 110 101 92 88 83 79 74 70 65 61 56 52 47 43 2 166 158 150 142 133 125 117 109 101 93 85 81 77 73 69 65 61 56 52 48 44 40 3 151 144 137 129 122 115 107 100 93 86 78 75 71 67 64 60 56 53 49 46 42 38 4 138 132 125 118 112 105 99 92 86 79 72 69 66 63 59 56 53 50 46 43 40 36 5 126 120 114 109 103 97 91 85 79 73 67 64 61 58 55 52 50 47 44 41 38 35 6 116 110 105 100 94 89 84 78 73 68 63 60 57 55 52 49 47 44 41 39 36 33 7 106 101 97 92 87 82 77 73 68 63 58 56 53 51 49 46 44 42 39 37 34 32 8 97 93 89 85 80 76 72 67 63 59 54 52 50 48 46 44 42 39 37 35 33 31 9 90 86 82 78 74 70 66 63 59 55 51 49 47 45 43 41 39 37 35 34 32 30 10 83 79 76 72 69 65 62 58 55 51 48 46 44 43 41 39 37 36 34 32 30 11 76 73 70 67 64 61 58 55 51 48 45 44 42 40 39 37 36 34 33 31 12 71 68 65 62 60 57 54 51 48 45 43 41 40 38 37 36 34 33 31 30 13 66 63 61 58 56 53 51 48 45 43 40 39 38 37 35 34 33 31 30 14 61 59 57 54 52 50 47 45 43 41 38 37 36 35 34 33 31 30 15 57 55 53 51 49 47 45 43 41 39 36 35 34 33 32 31 30 16 53 52 50 48 46 44 42 40 39 37 35 34 33 32 31 30 17 50 48 47 45 43 42 40 38 37 35 33 33 32 31 30 18 47 46 44 43 41 40 38 37 35 34 32 31 31 30 19 44 43 42 40 39 38 36 35 34 32 31 30 20 42 41 39 38 37 36 35 33 32 31 30 21 40 39 38 36 35 34 33 32 31 30 22 38 37 36 35 34 33 32 31 30 23 36 35 34 33 32 32 31 30 24 34 34 33 32 31 30 30 25 33 32 31 31 30 26 32 31 30 30 27 30 30 06.05.2006
3 rd Party Corrosion Testing RESISTANCE TO CUI Resistance to CUI exposure at 130 C internal temperature The externally coated pipe was filled with Shell Thermal B oil with four internal and four external thermocouples. One internal and one external thermocouple were positioned so they were at the same position to enable the measurement of the temperature difference. The sets of thermocouples were at different depth and equally spaced around the pipe. The oil was heated to 130 C and held for 100 days. During the 100 days the coating was sprayed with artificial seawater periodically over every 24 hours. Before the exposure test the coating has 020mm holidays milled through the coating to the substrate at three locations and saw cuts were made through the coating at the top and bottom of the cornered joint. CUI Exposure Test Test Specification BC/BP/JC issue 1 revision C Result After completing the exposure the coating exhibited no visible signs of cracking, flaked or disbondment. CUI Exposure Test Rating Assessment After Exposure Test Specification Assessment Rating BS 3900 Part H2 Degree of Blistering 2(S4) BS 3900 Part H3 Degree of Rusting Ri3 (less than 1%) BS 3900 Part H4 Degree of Cracking 0(0) BS 3900 Part H5 Degree of Flaking 0(0) Graph: CUI exposure test Nansulate showed consistent performance over the 97 day test timeline.
3 rd Party Thermal Conductivity Testing THERMAL CONDUCTIVITY Thermal conductivity exposure 60 C to 130 C The externally coated pipe was filled with Shell Thermal B oil with four internal and four external thermocouples. One internal and one external thermocouple were positioned so they were at the same position to enable the measurement of the temperature difference. The sets of thermocouples were at different depth and equally spaced around the pipe. The oil was heated to 60 C and held for 24 hours then increased to 90 C and held for 24 hours then increased to 110 C and held for 24 hours then increased to 130 C. Thermal Conductivity Test Test Specification BC/BP/JC issue 1 revision C Result After completing the exposure the coating exhibited no visible signs of cracking, flaked or disbondment. CUI Exposure Test Rating Assessment After Exposure Test Specification Assessment Rating BS 3900 Part H2 Degree of Blistering 2(S4) BS 3900 Part H3 Degree of Rusting Ri3 (less than 1%) BS 3900 Part H4 Degree of Cracking 0(0) BS 3900 Part H5 Degree of Flaking 0(0) Graph: Thermal conductivity test Nansulate